Friction Stir Welding Head Control for Load-Based Z-Axis Correction
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Solution Overview
Problem
Existing friction stir welding apparatuses are not effective in accurately correcting the welding tool position in a short time when the load factor exceeds a predetermined range, leading to suboptimal welding quality, especially when the excess is within a range where the required quality can still be maintained.
Innovation Solution
A friction stir welding apparatus with a control unit that implements a first correction mode using a variable correction quantity for small deviations and a second correction mode with a preset fixed correction quantity for larger deviations, allowing precise adjustment of the welding tool position within predetermined threshold values to maintain the load factor within a desired range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed correction value is used to correct the welding tool position when the load factor exceeds the predetermined range, then the correction is simple and quick, but the welding quality deteriorates when the exceeded quantity is small because the correction is too large and causes overshooting
Solution Approach 1:
The patent applies dynamics by making the correction value variable rather than fixed. The correction value is dynamically adjusted based on the magnitude of the load factor deviation from the predetermined range. When the deviation is large, a larger correction value is applied for quick correction; when the deviation is small, a smaller correction value is applied to avoid overshooting and maintain welding quality. This dynamic adjustment resolves the contradiction between correction speed and welding quality.
Solution Approach 2:
The patent changes the parameter of correction value from a fixed constant to a variable parameter that depends on the load factor deviation. By establishing a relationship between the deviation magnitude and the correction value, the system can adaptively select appropriate correction amounts. This parameter change enables the system to achieve both fast correction for large deviations and precise control for small deviations, resolving the technical contradiction.
2Device complexity
If correction is only performed when the load factor exceeds the predetermined range, then the control is simple, but the welding quality deteriorates because corrections are delayed until the threshold is crossed
Solution Approach 1:
The patent applies preliminary action by performing correction before the load factor exceeds the predetermined range. By monitoring the load factor continuously and initiating correction when approaching the threshold (rather than waiting for exceedance), the system proactively maintains the load factor within the optimal range. This preliminary correction prevents quality deterioration while maintaining relatively simple control logic.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the load factor and using this information to adjust the welding tool position. The correction amount is determined based on the feedback from the load factor measurement, creating a closed-loop control system. This feedback mechanism enables timely and appropriate corrections that maintain welding quality without requiring complex control algorithms.
3Loss of time
If a large correction value is applied when the load factor exceeds the range, then the load factor returns to the range quickly, but the welding quality deteriorates due to excessive correction and potential overshooting
Solution Approach 1:
The patent resolves this contradiction by making the correction value dynamic rather than fixed. The correction value is adjusted according to the magnitude of the load factor deviation: larger deviations receive larger correction values for quick recovery, while smaller deviations receive smaller correction values to prevent overshooting. This dynamic approach achieves both fast correction and maintenance of welding quality.
Solution Approach 2:
The patent changes the correction value parameter from a constant to a variable that scales with the deviation magnitude. By establishing a proportional relationship between deviation size and correction amount, the system optimizes the correction time-quality trade-off. This parameter change enables adaptive correction that is both efficient and precise.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate and timely correction of the welding tool position, ensuring high-quality friction stir welding by adjusting the position based on calculated deviations, thereby maintaining the required welding quality even when the load factor is close to the threshold values.
Implementation Method 1
friction stir welding (FSW) in which welding target materials are welded to each other by softening the welding target materials by frictional heat generated by rotating a cylindrical welding tool and stirring the softened portion
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A friction stir welding apparatus includes a welding tool that includes a shoulder and a probe supported by the shoulder, is inserted into a plurality of welding target members, and moves while rotating to weld the plurality of welding target members, a spindle motor that is coupled to the welding tool to rotate the welding tool in a predetermined direction, a welding head that supports the spindle motor, and an apparatus body that supports the welding head, applies a drive signal to the spindle motor, and moves the welding tool along a welding line while rotating the welding tool. The apparatus body has a first correction mode in which a welding tool position indicating a position of the welding tool in a Z-axis direction is corrected based on a variable correction quantity calculated by a predetermined operational expression according to a fluctuation quantity of a state quantity indicating a control quantity of the welding head in a Z-axis upper direction or a Z-axis lower direction when friction stir welding is performed on the welding target members by the welding tool, and a second correction mode in which the welding tool position is corrected based on a preset fixed correction quantity according to the fluctuation quantity.